Centrifugal switch



Dec. 7, 1948. J. H. SREB 2,455,620

CENTRIFUGAL SWITCH Filed Sept. 12, 1944 FIE FE;

3% clxW mfi 2% WW Patented Dec. 7, 1948 CENTRIFUGAL SWITCH Jules H.Sreh, Silver Spring, Md., assignor to the United States of AmericaSecretary of War as represented by. the

Application September 12, 1944, Serial No. 553,738 9.,Claims. (Cl.roe-10.2)

My invention relates to an improved centrifugal switch, and its generalobject is to .provide a device 01' this character wherein means isemployed for closing an electric circuit at the end of a predeterminedperiod of time.

A further object of my invention is to provide a device of thischaracter, wherein granules of electrical conducting material, suspendedin a fluid, are moved by centrifugal force into engagement with a pairof electrical contacts for closing an electric circuit.

A still further object of my invention is to provide a device or thischaracter, which is particularly adapted for use in connection with theelectrical detonating of artillery and like projectiles. l

A still further object of my invention is to provide a device of thischaracter which is of simple construction, and which is capable ofmanufacture at low cost.

vWith these and other objects in view, aswill v hereinafter more fullyappear and which will be more particularly pointed out in the appendedclaims, reference is now made to the accompanying drawings forming apart of this application,

in which:

Figure 1 is a perspective view of my improved centrifugal switch;

Figure 2 is a vertical section view, taken on the line 22 of Figure 1;

Figure. 3 is a top plan view, partly in section of my invention; and

Figure 4 is a vertical sectional view, partly in elevation showing myimproved switch in operative position in a projectile.

Referring now to the drawings in which similar reference charactersrepresent similar parts, in Figs. 1 and 2 my invention comprises a body,shown generally at 2, cylindrical in form preferably cast or moulded ofLucite or other suitable insulating material, and provided with acentral circular opening adapted to receive a magnet l0. Magnet III isprovided with a stud l2 at one end thereof, the other end being threadedto receive cap I, as shown in Fig. 2. Magnet I0 is also provided with anannular shoulder portion l6 and suitable conventional washers i8 and 20may be employed to prevent leakage.

The body 2 is provided with a radially extending cylindrical bore orchamber 2| which is threaded at its outer end to receive'a conventionalplug 22, preferably of the same material as is the body 2. Carried inthe body 2 and projecting into the bore 2| are contacts 24 and 26 ofcopper or other suitable electric current conducting material. Leadwires 2. and it are attached to the contacts and are connected in adetonator circuit, as shown in Figure 4. Carried in the bore 2i is afluid 34, which may consist of glycerine, oil, or some other liquidhaving the desired viscosity. Suspended in the fluid 34 is a pluralityof. granules 36, such as iron filings or other suitable electric currentconducting particles.

As best seen in Figure 4, the body 2 is mounted in a projectile,preferably on the axis thereof, when the projectile is at rest, themagnet will attract and retain the granules of electric conductingmaterial at the inner end of the chamber, as shown in Figs. 2 and 3, andout of engagement with the contact pins 24 and 28. When the projectileis fired, and after "set-back has diminished, centrifugal force willdrive the granules outwardly within the bore SI and through the solution34 into engagement with the contact pins, thereby closing an electriccircuit. In this connection it is pointed out that the centriiugal forcewill be sufllcient to drive the granules into engagement with and aboutthe contact pins with such effect that a low resistance connectionbetween said pins will be assured. When spin has ceased, the granuleswill fall away from the pins, causing a break in the circuit forproviding an extremely high resistance therethrough).

It is desired to call attention to the fact that, by providing solutionsof diflferent viscosities, a time delay may be imposed. That is to say,if solutions of heavy viscosity are employed, it will take a longer timefor centrifugal force to drive the granules into contact with the pinsthan would be the case if a solution of light viscosity were used.

It should also be understood that variousmodifications may be resortedto without departing from the spirit of the invention. For example, ifit is desired to use the device for breaking a short circuit, ratherthan closing a circuit, the pins may be mounted near the inner end ofthe chamber; It should also be understood that the magnet may beeliminated ii desired. However, it is believed that a greater factor ofsafety will be present if the magnet is employed when a magneticmaterial is used. In addition, a number of switches can be mounted inone body. Such switches may be employed for controlling a plurality ofelectric circuits in an electrically detonated projectile. For eXampleone of said switches could be used to break a short circuit,

anotherto close a filament circuit. and still another to close a platecircuit.

It should be understood that, if desired, a setback switch may beused inservice with my improved centrifugal switch so that electric potentialswill not be impressed on the switch contacts until after. the projectileis fired.

It is also desired to point out that, if different metallic colloids areused, the times at which the contacts will be bridged may be varied. Inaddition, by the use of metallic granules supported in a more or lessviscous solution, it will be possible to close a circuit gradually withthe result that the effect of transients will be minimized.

While I have illustrated and described the invention in some detail, itis to be understood that the invention is not to be limited to suchdetails. but only by the spirit of the invention and the scope of theappended claims.

I claim:

1. A switch of the character described com-prising a body, 'a chamberwithin said body, contact pins mounted in the chamber, and a pluralityof granules of electrical conducting material in the chamber andsuspended in a. fluid, said granules being adapted to be shifted bycentrifugal force for connecting the contact pins electrically with eachother.

2. A switch of the character described comprising a body, a radialchamber within said body, a

fluid in said chamber, a pair of contact pins mounted in said chamber, aplurality of granules possessing electrical conducting qualitiessuspended in said fluid, and centrifugal means for moving said granulesinto contact with said pins, said contact forming an electricalconnection between said pins.

3. A switch of the character described comprising a body. a chamberwithin said body, contact pins mounted in the chamber, a magnetpositioned in said body, a plurality of granules of electricalconducting material in the chamber and suspended in a fluid, saidgranules being adapted to be shifted by centrifugal force for connectinthe contact pins electrically with each other.

4. A switch of the character described comprising a body, a radialchamber within said body, a fluid in said chamber, a pair of contactpins mounted in said chamber, a magnet positioned in said'body, -aplurality of granules pcssessing electrical conducting qualitiessuspended in said fluid, and centrifugal means for moving said granulesinto contact with said pins, said contact forming an electricalconnection between said pins.

5. A switch of the character described com prising an annular body, amagnetic core mounted axially in said'body, a chamber within said bodyand extending radially from said magnetic said granules into contactwith said pins. said contact forming an electrical connection betweensaid pins. 1

6. A switch of the character described comprising an annular body, amagnetic core mounted axially in said body, a chamber within said bodyand extending radially from said magnetic core. a pair of contact pinsmounted in said chamber adjacent its outer end and adiacent each other,a fluid in said chamber, a plurality of electrical conducting granulessuspended in said fluid and normally maintained in juxtapositioncontiguous said magnetic core, and centrifugal means for moving core, apair of contact pins mounted in said cham- 60 ber near the outer end ofthe chamber and adjacent each other, a fluid in said chamber, aplurality of electrical conducting granules suspended in said fluid andcentrifugal means for moving said granules away from said position intocontact with said pins, said contact forming an electrical connectionbetween said pins.

7. A switch of the character described comprising an annular body. aradially extending chamber within said body. a magnetic core mountedaxially in said body and constituting the inner end of said chamber. apair of contact pins mounted in said chamber adjacent the outer endthereof and adjacent each other, a fluid in said chamber, a plurality ofelectrical conducting granules suspended in said fluid and centrifugalmeans for moving said granules into contact with said pins, said contactforming an electrical connection be tween said pins. I

8. A switch of the character described comprising a body. a chamberwithin said body, contact pins mounted in the chamber, a plurality ofgranules of electrical conducting material in the chamber and suspendedin a fluid, said granules being adapted to be shifted by centrifugalforce for connecting the contact pins electrically with each other, andmagnetic means for breaking said contact upon cessation of said centrifu1 force.

9. A fuze comprising a detonator adapted to be ignited by electricalmeans, a switch of the character described adapted to be mounted in anexplosive projectile, comprising a body, a chamber within said body,contact pins mounted in the chamber, a plurality of granules ofelectrical conducting material in the chamber and suspended in a fluid,said granules being adapted to be shifted by centrifugal force forconnecting the contact pins electrically with other other. and means forconducting the current to the detonator of said fuze.

JULES H. SREB.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,558,784 Bleecker Oct. 27, 19251,776,796 Ruhlemann Sept. 30, 1930 FOREIGN PATENTS Number Country Date149,723 Austria May 25, 1937

